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Polymers and Polymer Composites

VISCOELASTIC CONSTITUTIVE MODEL OF UNVULCANIZED RUBBER

July 1, 2005 By: Li Yong; Wu Jing'an; Du Xingwen Research article

Title: VISCOELASTIC CONSTITUTIVE MODEL OF UNVULCANIZED RUBBER
Page Range: p.727-36
Author(s): Li Yong; Wu Jing’an; Du Xingwen
File size: 224K
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Journal: Polymers and Polymer Composites
Issue Year: ppc
Volume: 13
Issue No: No. 7

Abstract
The rheological properties were examined experimentally using the inner-ply rubber of a bias tyre whose formula contains natural rubber, polybutadiene rubber, styrene butadiene rubber and two types of carbon blacks. On the basis of these rheological test results, a new viscoelastic constitutive equation for unvulcanised rubber has been established, with mathematical justification to describe its mechanical properties in relation to the yield stress and shear-thinning effect. The proposed model indicates that the yield stress is one of the main causes of the shear-thinning effect, and reveals why some materials possess double-Newtonian regions with the shear viscosity in the first region higher than that in the second region. The yield stress makes the flow index of the power law fluid model vary widely, so that it needs to be eliminated from the power law fluid model. The model can also effectively distinguish the true shear viscosity from the apparent shear viscosity, it is claimed. The parameters of the equation are determined by the step fitting method, which is the precondition for quantitative analysis. Since the equation is a one-dimensional model, the authors acknowledge the need for further research. 10 refs.

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